Maize Water Productivity and Its Impacts on Non-Renewable Groundwater Resources in Semiarid Climates

Recent satellite observations revealed rapid groundwater declines in many semiarid regions of the world where crop production heavily relays on irrigation, raising concerns regarding our ability to meet the raising demand for food, feed, and fiber if these large reserves of non-renewable freshwater are to be heavily exploited in the future. To preserve groundwater resources, many regulatory agencies started defining the maximum amount of water applied through irrigation forcing farmers devise a strategy that will maximize the grain yield and profit to the amount of irrigation water available (i.e., deficit irrigation). Consequently, larger pressure has been put on plant breeders towards identification and selection of genotypes with improved yield and water productivity under water stress conditions. Occupying the largest portions of the worldwide cropland (both rainfed and irrigated), maize has been both cause and a solution to the problems revolving around global food and water security. The work presented here investigated the effects of genetic, environmental, and management factors on maize water productivity from three different perspectives: (1) contributions of genetic improvements to overall increase in maize yield and water productivity during the 1960s-2000s period, (2) variability of maize water productivity responses among the most recent hybrid releases, and (3) potential gaps in knowledge that, if exploited, could lead to improved maize water productivity in the future